Artificial sweeteners make consumers hungrier, Uni of Sydney study

A new study out of the University of Sydney has discovered why artificial sweeteners can make both humans and animals hungrier.

Published today in the Cell Metabolism journal, the study found a system in the brain that senses and integrates the sweetness and energy content of food.

“After chronic exposure to a diet that contained the artificial sweetener sucralose, we saw that animals began eating a lot more,” Associate Professor Neely said.

“Through systematic investigation of this effect, we found that inside the brain’s reward centres, sweet sensation is integrated with energy content. When sweetness versus energy is out of balance for a period of time, the brain recalibrates and increases total calories consumed.”

How the study worked

In the study, fruit flies that were exposed to a diet laced with artificial sweetener for prolonged periods (more than five days) were found to consume 30 percent more calories when they were then given naturally sweetened food.

“When we investigated why animals were eating more even though they had enough calories, we found that chronic consumption of this artificial sweetener actually increases the sweet intensity of real nutritive sugar, and this then increases the animal’s overall motivation to eat more food,” said Associate Professor Neely.

This is the first study conducted to identify how artificial sweeteners can stimulate appetite. The study also discovered artificial sweeteners promoted hyperactivity, insomnia and decreased sleep quality.

To help see whether the scientists could find the same findings in mammals as they did in the fruit flies, mice were also fed artificial sweeteners to the same effect.

“These findings further reinforce the idea that ‘sugar-free’ varieties of processed food and drink may not be as inert as we anticipated,” said Professor Herbert Herzog, the scientist who replicated the study using mice.

“Artificial sweeteners can actually change how animals perceive the sweetness of their food, with a discrepancy between sweetness and energy levels prompting an increase in caloric consumption,” Professor Herzog said.